Question

Write a short research paper to give a summary of different fiber optic technologies used for client layers.

Answer 1

What Is Optical Fiber Technology

Fiber optics, or optical fibers, are long, thin strands of carefully drawn glass about the diameter of a human hair. These strands are arranged in bundles called optical cables. We rely on them to transmit light signals over long distances.

At the transmitting source, the light signals are encoded with data… the same data you see on the screen of a computer. So, the optical fiber transmits “data” by light to a receiving end, where the light signal is decoded as data. Therefore, fiber optics is actually a transmission medium – a “pipe” to carry signals over long distances at very high speeds.

Fiber optic cables were originally developed in the 1950s for endoscopes. The purpose was to help doctors view the inside of a human patient without major surgery. In the 1960s, telephone engineers found a way to use the same technology to transmit and receive telephone calls at the “speed of light”. That is about 186,000 miles per second in a vacuum, but slows to about two-thirds of this speed in a cable.

Connectors Early fiber optic connections involved cutting the fiber, epoxying a special connector, and polishing the end of the fiber. This operation required special tools and testing equipment to ensure a good connection. While this technique is still used, devices used to cut, align and join fibers have been improved and simplified. Connection losses vary, depending on the type of connection but typically range from 0.2 dB to 1 dB. There are several standard connector types used to join or terminate fiber optic cables. These include: Used where high density interconnections are required 1. ST : Used in inter/intra building, security, Navy and industrial applications (also used with some B&B Electronics products) 2. SC Duplex & SC: Used in data communications and telecommunications applications (also used with some B&B Electronics products) 3. FC : Used in data communications and telecommunications applications 4. FDDI : Used in some fiber optic networks 5. MTArray $ LC: Used where high density interconnections are required The most important consideration in planning the fiber optic link is the power budget specification of the devices being connected. This value tells you the amount of loss in dB that can be present in the link between the two devices before the units fail to perform properly. This value will include line attenuation as well as connector loss.PLANNING A FIBER OPTIC LINK Power Budget Example For B&B Electronics’ 9PFLST Port-Powered RS-232 Fiber Optic Modem the typical connector-to-connector power budget is 12.1 dB. Because 62.5/125 µm cable typically has a line attenuation of 3 dB per km at 820 nm, the 12.1 dB power budget translates into 2.5 miles (4 km). This assumes no extra connectors or splices in the link. Each extra connection would typically add 0.5 dB of loss, reducing the possible distance by 166 m (547 ft.) Your actual loss should be measured before assuming distances. When the 9PFLST is used without external power, the power available to the Fiber Optic transmitter may be less than the typical value. The link should be tested with the 9PFLST in place with a variable attenuator to check the optical power budget of the whole system. ADVANTAGES OF FIBER OPTIC CABLES Noise Immunity Noise immunity is one of the most useful features of fiber optics in industrial applications. In environments where electromagnetic interference is prominent and unavoidable, fiber optics are unaffected. While cables are normally contained in protective sheaths and often run inside conduit, there is no need to physically isolate fiber optic cables from electrical cables. This makes cable routing simpler. Electrical Isolation The problem of ground loop noise and common mode potential differences is eliminated by the use of fiber optic cables. Field signals, generated by devices floating at high potentials, can be coupled to other equipment at much lower potentials without the risk of damage. This is particularly desirable in industrial applications. Low Error Rates When properly designed to provide adequate signal levels at the receiving end of the link, a fiber optic system provides very low bit error rates. Safe for Use in Hazardous Areas Fiber optic links can be used to couple signals into areas with potentially explosive atmospheres without a risk to delivering or storing sufficient energy to ignite an explosion. This makes fiber optic technology particularly useful when designing intrinsically safe systems. Wide Bandwidth Fiber optic cables can carry very wide bandwidth signals, well into the GHz range. Many individual, lower bandwidth signals can be multiplexed onto the same cable. In commercial systems fiber optic cable often carries a mixture of signal types, including voice, video and data all on the same fiber. Low Signal Attenuation Optical fibers do exhibit some attenuation due to absorption and scattering. However, this attenuation is relatively independent of frequency, a factor that is significant in copper cables. Light Weight, Small Diameter Because many signals can be multiplexed onto one fiber, cables tend to be smaller and lighter. This makes installation easier. No Crosstalk Since fibers do not pick up electromagnetic interference, signals on adjacent cables are not coupled together. Inherent Signal Security For applications where signal security is a concern, optical fiber is an excellent solution. Fiber optic cables do not generate electromagnetic fields that could be picked up by external sensors. It is also more difficult to 'steal' signals by spicing into optical fibers than it might be with conventional copper wiring.